Kobi (Jacob) Lasri Ophir Optronics Solutions Ltd., MKS Instruments
Presented at the International Conference on Optics & Electro Optics (ICOL), India, 2019.
Infrared imaging applications are evolving at a rapid pace and continue to drive challenging requirements for reduced Size, Weight, and Power (SWaP). In particular, applications like Hand Held Thermal Imagers (HHTI), UAV, and small gimbals present a growing need for advanced, high-performance, IR thermal imaging systems with reduced size and weight. While advances in detector resolution should improve imaging performance, this is impossible without an accompanying improvement in the quality of the IR optical lens assembly. Specifically, in optics-limited systems, lens quality is playing a major role in determining the imaging performance, even with the best detector. The challenge falls on lens providers to design and produce compact, lightweight lenses with a crisp clean image over the entire zoom range and an MTF close to the diffraction limit. In this vein, various technologies are being used to meet these optical needs, including innovative opto-mechanical designs , exotic materials [2,3], and free-form optics . In this report we demonstrate advanced designs of two continuous IR zoom lenses with reduced SWaP based on unique folded-optic and lightweight opto-mechanical concepts, respectively, suitable for next generation IR cooled detector and thermal imaging applications with constrained platforms.
Two examples of SWaP zoom lenses for cooled MWIR IR sensors are described. The first is a 16-180mm f/3.6 continuous zoom lens in a folded-optic configuration suitable for compact gimbaled payloads with 10µm pixel cooled detectors. The second SWaP example is a 20-275mm f/5.5 continuous zoom lens with a unique light-weight opto-mechanical design suitable for UAVs, drones, and HHTI applications.
Figures 1(a) demonstrates the opto-mechanical layout and picture of the LightIR 16-180mm f/3.6 zoom lens optimized for MWIR 10µm pixel detectors. The design is based on a standard relay and objective configuration with two moving groups that allow for the change in the focal length. The materials were selected using best practices, as well as the athermalization and achromatization concepts.